Microencapsulated composition containing chlorpyrifos or endosulfsan

ABSTRACT

The present invention relates to a microencapsulated chlorpyrifos or endosulfan composition comprising a polyurea shell and one or more photostable ultraviolet and visible light absorbent compound having a log molar extinction coefficient of from about 2 to 5 with respect to radiation having wave lengths in the range of about 310 to 450 nanometers, wherein said photostable ultraviolet and visible light absorbent compound does not react with the monomer used in building the polyurea shell. The result is a microencapsulated composition having unexpected long, extended insecticidal activity with high toxicity to target species and very low toxicity to non-target animals.

BACKGROUND OF THE INVENTION

The present in vent ion relates to microencapsulated insecticide compositions which are stabilized against environmental degradation. The present invention more specifically relates to microencapsulated chlorpyrifos or endosulfan stabilized against degradation by visible and ultra-violet light having unexpected extended insecticidal activity while having unexpected low toxicity to non-target species.

Chlorpyrifos, which is the common name for O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)-phosphorathio- ate, is a well-known insecticide. Two major problems of this insecticide is on the one hand its ease of decomposition when exposed to the environment and the concomitant high toxicity to non-target animals. Thus, technical chlorpyrifos has a toxicity to rats (acute oral) of an LD₅₀ of 168 mg/kg and a toxicity to trout (acute) of an LC₅₀ of 0.007 mg/kg.

Endosulfan, which is the common name for 6,7,8,9,10-hexachloro-1,5-5a,9a tetryhydro-6,9-methano-2,4,3-benzodioxathipia-3-oxide, is also a well-known insecticide, with stability and toxicity problems. Its toxicity problem is most acute to non-target species such as fish and bees as the technical material has an LD₅₀ to non-target species such as mice of 30 mg/kg. For an EC formulation to classified as "only harmful" its LD₅₀ to mice must be at least 200 mg/kg. However, to reach such a toxicity, the concentration of endosulfan must be dropped to 3%, resulting in a non-economical mixture of very low activity.

The microencapsulation of pesticides and insecticides has been proposed in the prior art as a way of extending the insecticidal life of pesticides while supposedly decreasing their toxicity to non-target animals. Examples are: U.S. Pat. Nos. 2,800,458; 3,069,370 , 3,116,216, 3,137,631, 3,270,100; 3,418,250; 3,429,827; 3,577,515; 3,959,164; 4,417,916; and 4,563,212. British Patent Number 1,371,179; European Patent Publication Numbers 148,169 and 165,227; and Israel Patent Numbers 79,575 and 84,910.

Microencapsulated chlorpyrifos has been reported in European Patent Application No. 140,548. Microencapsulated endosulfan has been reported in U.S. Pat. No. 4,230,809. in neither case is there any report of the use of ultraviolet absorbers in these microencapsulated formulations.

The use of an ultraviolet absorber to protect insecticides, especially pyrethroids, has been reported in U.S. Pat. Nos. 2,168,064; 3,063,893; 3,098,000; 3,130,121; 3,264,176; 3,541,203; 3,560,613; and 3,839,561.

U.S. Pat. Nos. 4,056,610 and 4,497,793 describe the use of specific UV absorbers in microencapsulated pyrethrins. However, these require the case of U.S. Pat. No. 4,056,610--the use of a UV absorber both the outer casing and in the liquid fill.

Regardless of the disclosure in the prior art, there has not yet been offered for sale microencapsulated chlorpyrifos or endosulfan, which has both extended insecticidal activity and extremely low toxicity to non-target animals.

SUMMARY OF THE INVENTION

According to the present invention there is provided a microencapsulated chlorpyrifos or endosulfan composition comprising a polyurea shell and one or more photostable ultraviolet and visible light absorbent compounds having a log molar extinction coefficient of from about 2 to 5 with respect to radiation having wave lengths in the range of about 310 to 450 nanometers wherein said photostable ultraviolet and visible light absorbent compound does not react with the monomer used in building the polyurea shell. The result is a microencapsulated composition having unexpected long, extended insecticidal activity with high toxicity to target species and very low toxicity to non-target animals.

DETAILED DESCRIPTION OF THE INVENTION

The microencapsulated insecticidal composition of the present inventions are prepared using standard processes. Details for chlorpyrifos appear in Example 1. Details for endosulfan appear in Example 10. The percentage of the envelope--excluding the water and the polyvinyl-alcohol varies from 3% to 50%, preferably up to 30%. Similarly, the fill contains from 0.5% to 5% preferably 1% to 3%, of the photostable ultraviolet and visible light absorbent compound.

Details of the stability of chlorpyrifos are listed in Example 2. For endosulfan, it was found that it decomposed after irradiation for 100 hours at 310±5 nanometers and 475± nanometers.

The photostable ultraviolet and visible light absorbent compounds are selected from the group consisting of sterically hindered amines and dyes. The sterically hindered amines are in turn selected from the Ciba-Geigy products known by the general trade name "TINUVIN" where the preferred ones are "TINUVIN -770" and "TINUVIN -780" having the following structures and Chemical Abstract Numbers as follows: ##STR1##

These ultraviolet and visible light absorbent compound were chosen among other reasons because they did not react with the monomers that build the envelope.

The microencapsulated compositions of the invention may also optionally contain in addition to one of the "TINUVINS" dyes selected from the group consisting of Thermoplast green, Blue paste, Fluorescein, Sudan blue, Macrolex blue and Sedan III.

The microencapsulated compositions containing chlorpyrifos are listed in Table 1. Several of these compositions were studied to determine which had the longest activity against larger species, such as beetles and cockroaches, even after exposure to sunlight, (Examples 4,5 and 8) while having the lowest toxicity to non-target species, represented by mice, fish and bees (Examples 3,6 and 9). The result was that composition Numbers 14 and 15 containing chlorpyrifos were the preferred compositions, with Number 14 most preferred.

Almost all of the microencapsulated compositions of the present invention containing endosulfan gave poor toxicological results on mice. That is, in order to obtain a formulation with an LD₅₀ of 200 for mice the formulation would have to be very diluted; making it commercially unacceptable. However, compositions numbers 59 and 61 showed appreciably lower toxicity to non-target species at a commercially viable concentration of endosulfan, with number 61 the best. Examples 11 and 12 show the toxicity of these two formulations against the non-target species represented by mice and fish, respectively.

Thus, the present invention affords a novel microencapsulated composition containing chlorpyrifos or endosulfan, which not only can withstand relatively long exposure to sunlight, has a low toxicity to non-target species such as mice, bees and fish, while retaining commercially acceptable toxicity levels to target species such as beetles and cockroaches.

While the invention will now be described in connection with certain preferred embodiments in the following examples, it will be understood that it is not intended to limit the invention to these particular embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the scope of the invention, as defined by the appended claims. Thus, the following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purposes of illustrate discussions of preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of procedures as well as of the principles and conceptual aspects of the invention.

EXAMPLE 1 Representative Preparation of the Microencapsulation of Chlorpyrifos

Four separate solutions: A, B, C and D were prepared as follows:

    ______________________________________                                         Solution A:                                                                              1520 ml water                                                                  15.2 g polyvinylalcohol ("MOWIOL-G-4)                                Solution B:                                                                              720 g melted chlorpyrifos                                                      140 g Voranate M-580                                                           4 g "TINUVIN-770"                                                    Solution C:                                                                              360 ml water                                                                   20 g ethylene diamine                                                          18.3 g diethylenetriamine                                            Solution D:                                                                              14 g propylene glycol                                                          58.4 Nonylphenol 6 mole ethoxylated (NP-6)                                     10 g xanthan gum                                                     ______________________________________                                    

Formation of the microcapsules is carried out by interfacial polymerization as follows:

A good emulsion of Solution B in A was made by mixing for 5 minutes in a high sheer mixer, keeping the mixture at 40° C. To this emulsion was slowly added Solution C, keeping the temperature at 40° C. The reaction mixture was cooled to 25° C. to 35° C. and the stirring was continued for 4 additional hours. Solution D was added and the mixture stirred for 15 minutes. Representative microencapsulated compositions of chlorpyrifos are listed in Table 1.

                                      TABLE 1                                      __________________________________________________________________________     REPRESENTATIVE MICROENCAPSULATED COMPOSITIONS OF CHLORPYRIFOS                          isocyanates                                                                              E.D.A.                                                                             DETA                                                                               PDA                                                                               Tinuvin 770                                                                          TEPA                                                                               Tinuvin P                                                                            TiO.sub.2                                                                         Escalol                        Formulation no.                                                                        types amount                                                                             (g) (g) (g)                                                                               (g)   (g) (g)   (g)                                                                               (g)  Water                                                                                PV                  __________________________________________________________________________                                                                (g)                  1.     ISONATE                                                                              35  6.2 5.7 -- 0.9   --  --    -- --   360   4                           M-309                                                                   2.     ISONATE                                                                              35  6.2 5.7 -- --              1  --   360                               M-302                                                                   3.     ISONATE                                                                              35  --  5.7 -- --    9.6 --    -- 1    360                               M-302                                                                   4.     ISONATE                                                                              35  --  5.7 -- 0.9   9.6 --    -- --   360   4                           M-302                                                                   5.     ISONATE                                                                              35  6.2 5.7 -- 0.9   --  --    -- --   380   3.8                         M-302                                                                   6.     Voranate                                                                             35  --  5.7 7.7                                                                               0.9   --  --    -- --   380   3.8                         M-580                                                                   7.     Voranate                                                                             35  6.2 5.7 -- 0.9   --  --    -- --   380   3.8                         m-220                                                                   8.     HMDI  2.61                                                                               6.1 5.7 -- --    --  1     -- --   360   6                    9.     HMDI  2.61                                                                               6.2 5.7 -- --    --  --    -- 1    360   .6                  10.     TDI   27  6.2 5.7 -- --    --  1     -- --   360   3.6                 11.     TDI   27  6.2 5.7 -- 1     --  --    -- --   360   3.6                 12.     TDI   27  --  5.7 -- --    9.6 1     -- --   360   3.6                 13.     Voranate                                                                             35  6.2 5.7 -- --    --  1     -- --   360   3.6                         M-580                                                                  14.     Vorante                                                                              35  6.2 5.7 -- 0.9   --  --    -- --   400   4                           M-580                                                                  15.     Voranate                                                                             280 39.7                                                                               36.8                                                                               -- 8     --  --    -- --   3040  30.4                        M-580                                                                  16.     Voranate                                                                             280 39.7                                                                               36.8                                                                               -- 8     --  --    -- --   3040  30.4                        M-580                                                                  17.     Voranate                                                                             280 39.7                                                                               36.8                                                                               -- 8     --  --    -- --   3500  35                          M-580                                                                  18.     Voranate                                                                             280 34.7                                                                               31.9                                                                               -- 9     --  --    -- --   3040  30.4                        M-580                                                                  19.     Voranate                                                                             4.4 0.62                                                                               0.58                                                                               -- 1     --  --    -- --   380   3.8                         M-580                                                                  20.     Voranate                                                                             35  4.2 4   -- 1     --  --    -- --   380   3.8                         M-580                                                                  21.     Voranate                                                                             140 20  18.3                                                                               -- 4     --  --    -- --   1520  15.2                        M-580                                                                  22.     Voranate                                                                             35  5.6 5.3 -- 1     --  --    -- --   380   3.8                         M-580                                                                  23.     Voranate                                                                             35  5.6 5.3 -- 1     --  --    -- --   380   3.8                         M-580                                                                  24.     Voranate                                                                             11.7                                                                               1.86                                                                               1.71                                                                               -- 1     --  --    -- --   380   3.8                         M-580                                                                  25.     Voranate                                                                             35  5   4.6 -- 1     --  --    -- --   380   8                           M-580                                                                  26.     Voranate                                                                             35  6.2 5.7 -- --    --  1     -- --   360   3.6                         M-580                                                                  __________________________________________________________________________      EDA  Ethylene diamine                                                          DETA  Diethylene triamine                                                      PDA  Propylene diamine                                                         TEPA  Tetra ethylene penta amine                                         

EXAMPLE 2 Stability of Unprotected Chlorpyrifos to UV/Visible Light

Unprotected chlorpyrifos was irradiated by an ultraviolet/visible light lamp for 68 hours. The stability versus the wavelength of the light is summarized as follows:

    ______________________________________                                         Wave Lengths      Extent of Degradation                                        ______________________________________                                         313 ± 5        Total degradation                                            365 ± 5        Low degradation                                              404 ± 5        Low degradation                                              436 ± 5        Medium degradation                                           ______________________________________                                          .sup.a In nanometers                                                     

EXAMPLE 3 Metthod for Determining Acute Oral Toxicity with Mice

It is preferable lo use Adult males (2-2.5 months) weighing 25-30 g. A solution of the formulation was obtained by using a "Vortex" mixer for 5 min. The quantity of the solution depended on the weight of mouse. Thus, 1 ml. solution was administered for 20 g of mouse weight. The solution was introduced by using a syringe (2 ml) through the mouth into the stomach of mouse. The test was performed in 5 replications and mortality was checked after 0,5,24,72,96,120,144,168 hours. Standardized mouse food was given during the experiment. The results for three composition of the present invention are listed in Table 2 together with the data for a standard Emulsifiable Concentrate formulation of chlorpyrifos after a time of 168 hours.

                  TABLE 2                                                          ______________________________________                                         ID.sub.50 ON MICE OF SEVERAL                                                   FORMULATIONS OF CHLORPYRIFOS                                                              LD.sub.50                                                           Formulation.sup.a          Formulation of                                      Number       Techincal Material.sup.b                                                                     250 g/l                                             ______________________________________                                          6           2250          9,000                                               13           2250          9,000                                               14           >2700         >10,800                                             E.C. formulation                                                                            120           480                                                 ______________________________________                                          .sup.a From Table 1                                                            .sup.b mg/kg                                                             

EXAMPLE 4 Method for Determining the Susceptibility of Beetles (Tribolium castaneum and Maladera matrida to Insecticides)

This method was used to measure the levels of susceptibility of population of beetles to a given insecticide. The method was carried out in a room free from insecticide contamination. The beetles were treated and held at a temperature of 30° C. for Tribolium castaneum and 25° C. for Maladera matrida and a relative humidity above 25%. Beetles were obtained, as far as possible, from the same area, and kept in a suitable container until required; and they were given adequate and standardized food before the experiment, Adult beetles of either sex were used. Tribolium castaneum were grown on flour enriched with 1% of beer yeast. Maladera matrida were obtained from the land of the farm "Sufa" and held in the laboratory in a suitable container on the ground which was used for food. A solution of each of the different formulations and the commercial material was obtained by using a high-shear mixer for 5 min, For each formulation Whatman paper No. 41 (d=9 cm.) was dipped into the solution during mixing and put into a petri dish (d=9 cm). The filter paper for exposure time 0 was dried in the hood, and the others were taken to the roof of the laboratory and exposed to sunlight. Approximately every 5 days, 3 petri dishes were removed from the roof and 5 beetles were placed inside each dish by using an aspirator for Trillium castaneum. The experiment was performed in 3 replications and mortality was checked each replication. The results for Maladera matrida treated with various chlorpyrifos compositions are shown in Table 3.

                  TABLE 3                                                          ______________________________________                                         Maladera matrida                                                               TREATED WITH VARIOUS CHLORPYRIFOS                                              MICROENCAPSULATED FORMULATIONS                                                                      Percent Killed                                            Exposure.sup.a                                                                          Concentration.sup.c                                                                        Formulation Type.sup.b                                    to sun   ppm         14     13   6    EC.sub.45                                                                           Blank                               ______________________________________                                          0       500         100    100  100  100  0                                    6                   86.7   100  100  53.3                                     10                   80     93.3 93.3 53.3                                     17                   6.7    0    33.3 0                                        ______________________________________                                          .sup.a In days                                                                 .sup.b From Table 1                                                            .sup.c Of chlorpyrifos                                                   

EXAMPLE 5 Method for Determining the Efficacy of Cockroaches (Germanica blatella) to Insecticides

This method measured the levels of susceptibility of a population of cockroaches to Chlorpyrifos. Cockroaches were exposed to standard chlorpyrifos residues in a petri dish and mortality was determined. From the results, the times necessary for 50% and 95% knockdown (LT₅₀ and LT₉₅) can be determined. Adult males were used. If it was not feasible to obtain enough males, information on susceptibility can be obtained by using females. The test was carried out in a room free of insecticidal contamination. The cockroaches were exposed to the chlorpyrifos and held at a temperature between 25° C. and 30° C. and at a relative humidity above 25%. Cockroaches were given adequate and standardized food before the experiment. Cockroaches, Germanica blatella were grown in the laboratory in containers with ready-to-serve meaty dog food.

A solution of each of the different formulations and the commercial material was obtained by using a high-shear mixer for 5 min. A solution of different concentrations was prepared. For each formulation Whatman paper N41 (d=9) was dipped into the solution during mixing and put in a petri dish (d=9). The filter paper for exposure time was dried in a hood and the others were taken to the roof of the laboratory and exposed to sunlight. Approximately every 5 days a petri dish was removed from the roof, and 5 Germanica blatella cockroaches were placed inside. To introduce 5 cockroaches into each petri dish, the cockroaches was first anaesthetized with carbon dioxide. The test was performed in 3 replications and mortality was checked. The exposure times examined were 0,5,10,15 and 20 days, approximately. Control dishes--untreated Whatman paper with 5 cockroaches after 24 h. A cockroach was considered knocked down if it fails to move on being returned to a normal posture. The results for various microencapsulated formulations of chlorpyrifos are shown in Tables 4 and 5.

The tests were carried out according to the World Health Organization Technical Report Series No. 443 Geneva 1970, pp 130-133.

                  TABLE 4                                                          ______________________________________                                         Germanicia blatella                                                            TREATED WITH VARIOUS CHLORPYRIFOS                                              MICROENCAPSULATED FORMULATIONS                                                                   Percent Killed                                               Exposure                                                                              Formulation                                                                               Concentration (ppm)                                          to Sun.sup.a                                                                          Type.sup.b 100    200  300  400  500  Blank                             ______________________________________                                         0      14         100    100  100  100  100  0                                 0      13         26.7   80   100  100  100                                    0       6         0      93.3 93.3 93.3 100                                    0      EMPIRE.sup.c                                                                              73.3   100  100  100  100                                    0      EW-20.sup.d                                                                               100    100  100  100  100                                    0      EC-45.sup.e                                                                               93.3   100  100  100  100                                    ______________________________________                                          .sup.a Hours                                                                   .sup.b From Table 1                                                            .sup.c Dow Chemical Company microencapsulated chlorpyrifos, 200 g/l            .sup.d Water based formulation of Makhteshim Chemical Works.                   .sup.e Standardized Emulsified Concentrate (nonmicroencapsulated)              formulation of chlorpyrifos.                                             

                  TABLE 5                                                          ______________________________________                                         Germanicia blatella                                                            TREATED WITH VARIOUS CHLORPYRIFOS                                              MICROENCAPSULATED FORMULATIONS                                                                   Percent Killed                                               Exposure                                                                              Formulation                                                                               Concentration (ppm)                                          to sun.sup.a                                                                          Type.sup.b 25     50   100  150  200  Blank                             ______________________________________                                         0      14         100    100  100  100  100  0                                 0      EMPIRE.sup.c                                                                              26.7   33.3 53.3 80   100                                    0      EC-45.sup.d                                                                               60     60   73.3 100  100                                    ______________________________________                                          .sup.a Hours                                                                   .sup.b From Table 1                                                            .sup.c Dow Chemicals Company microencapsulated chlorpyrifos, 200 g/l           .sup.d Standardized Emulsified Concentrate (nonmicroencapsulated)              formulation of chlorpyrifos.                                             

EXAMPLE 6 Methhod for Determining Toxicity of Fish (Guppies)

All guppies require about the same basic care: water quality as close as possible to pH=7.0 (neutral); water temperature about 24°-25° C., and good strong light for least 12 hours a day (more light makes them grow faster). The test method was carried out in a room free of insecticidal contamination. Adult fish of either sex were used.

Guppies were obtained from a fish shop and kept in a suitable 16-liter aquariums (water temperature 23°-25° C.), 10 fish/aquarium, The guppies were given adequate and standardized food (Europet Basic Food) before and after the experiment. Food was withheld for 2 days before the experiment.

Solutions of formulation and commercial material were obtained by using a high-shear mixer for 5 min. Solutions 250,500,100,2000,4000,5000, μg/liter of the formulations were prepared. Mortality was checked after 3,6,24,48,72 and 96 hour. From the results, the times necessary for 50% and 95% mortality (LT₅₀ and LT₉₅) can be determined for each formulation. Test were carried out also on with golden orfe fish. The results are listed for golden orfe fish in Table 6.

                  TABLE 6                                                          ______________________________________                                         TOXICITY OF A CHLORPYRIFOS                                                     MICROENCAPSULATED FORMULATION                                                  TO GOLDEN ORFE FISH                                                            Concentration (μg/l)                                                        of Formulation 14                                                              Percent Killed           EC (μg/l).sup.b                                    5000      2000     1000    250   50  250                                       Time.sup.a                                                                            Percent Killed                                                          ______________________________________                                          0      0      0        0    0      0   0                                       3     100     0        0    0      0   0                                       6     100     0        0    0      0  10                                      24     100    30       10    0      0  10                                      48     100    40       20    0     10  30                                      72     100    40       20   10     10  30                                      96     100    40       20   10     20  30                                      ______________________________________                                          .sup.a Hours                                                                   .sup.b Standardized Emulsified Concentrate (nonmicroencapsulated)              formulation of chlorpyrifos.                                             

EXAMPLE 1 Microencapsulated Chlorpyrifos using Variations of Formulation 14 and Containing Various Concentrations of Dyes

Following the method of Example 1, one of the preferred microencapsulated formulation, Type 14 was prepared containing various different dyes. The microencapsulated formulations prepared are shown in Table 7.

                                      TABLE 7                                      __________________________________________________________________________     VARIATIONS OF FORMULATION TYPE 14 CONTAINING VARIOUS DYES                                               Tinuvin                                               Formulation                                                                           Isocyanate                                                                               EDA DETA                                                                               770  Colour                                           Number Type Amount                                                                              (g) (g) (g)  type   amount (g)                                __________________________________________________________________________     14-G   Voranate                                                                            35   5.0 4.6 1    Thermoplast                                                                           1                                                M-580                  green                                            14-H   Voranate                                                                            35   5.0 4.6 1    Blue paste                                                                            1                                                M-580                                                                   14-I   Voranate                                                                            35   5.0 4.6 1    Fluorescein                                                                           1                                                M-580                                                                   14-J   Voranate                                                                            35   5.0 4.6 1    Sudan Blue                                                                            1                                                M-580                                                                   14-K   Voranate                                                                            35   5.0 4.6 1    Macrolex                                                                              0.25                                             M-580                  Blue                                             14-L   Voranate                                                                            35   5.0 4.6 1    Sudan III                                                                             1                                                M-580                                                                   14-M   Voranate                                                                            35   5.0 4.6 1    Sudan III                                                                             1                                                M-580                                                                   14-N   Voranate                                                                            157.5                                                                               22.3                                                                               20.7                                                                               4.5  Macrolex                                                                              1.5                                              M-580                  Blue                                             14-O   Voranate                                                                            259  36.7                                                                               34  7.7  Macrolex                                                                              3.0                                              M-580                  Blue                                             14-P   Voranate                                                                            140  19.8                                                                               18.4                                                                               4    Macrolex                                                                              1.6                                              M-580                  Blue                                             14-Q   Voranate                                                                            385  54.5                                                                               50.6                                                                               11   Sudan Blue                                                                            4.4                                              M-580                                                                   14-R   Voranate                                                                            420  59.5                                                                               55.2                                                                               12   --     --                                               M-580                                                                   14-S   Voranate                                                                            385  54.5                                                                               50.6                                                                               11   Sudan Blue                                                                            4.4                                              M-580                                                                   14-T   Voranate                                                                            525  74.4                                                                               69  15   Sudan Blue                                                                            6                                         __________________________________________________________________________

EXAMPLE 8

Following the method of Example 4, several microencapsulated formulations of chlorpyrifos were compared as to their effect against Tribolium castaneum in petri dishes after exposure to sunlight. Results are shown in Table 8.

                                      TABLE 8                                      __________________________________________________________________________     COMPARISON OF SEVERAL ENCAPSULATED FORMULATIONS ON                             TRIBOLIUM CASATANEUM AFTER EXPOSURE TO SUNLIGHT                                CONCENTRATION 500 P.P.M.                                                       Exposure                                                                       to sun                                                                              Formulation type                                                          light                                                                               EC 14A                                                                               14 13 21 19 2  3  4  5  6  8  9  Penn phos.                         days Percent Killed                         Penn wall                          __________________________________________________________________________      0   100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                 5    6 100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                                                               100                                10    6 100                                                                               100                                                                               100                                                                               100                                                                               100                                                                                76                                                                                20                                                                                33                                                                                26                                                                                80                                                                               100                                                                               100                                                                                25                                15    0  0  60                                                                                10                                                                                36                                                                                56                                                                                13                                                                                0  0  23                                                                                0  50                                                                                40                                                                                25                                __________________________________________________________________________      .sup.a EC                                                                

EXPERIMENT 9 Toxicity (Acute Contact and Oral LD₅₀) of Microencapsulated Chlorpyrifos to Honey Bees (Apir mellifera L.)

A. General

The study was performed with worker honey bees of about the same age, bred in a normal beekeeper's manner. For the tests, the bees were caught from the entrance hole of the hives in groups of ten with glass capture tubes, without anesthetics. During the tests, the bees were provided ad libritum with commercial ready to use syrup for honey bees as food. Stainless steel chambers (width 10 cm, height 8.5 cm, and depth 5.5 cm) served as test cages. The inner sides of the cages (except the front side) were covered with filter paper. The test cages were exposed in incubators at about 28° C., at 40 to 60% relative humidity in darkness, while being ventilated to avoid possible accumulations of pesticides vapor. The tests were performed in five dosages of microencapsulated chlorpyrifos and one solvent control with three replicates per dosage or control.

B. Contact Toxicity Test

First the test cages with the bees in it were exposed to CO₂ in an incubator to anaesthetize the test animals with CO₂ dosage chosen so that the anaesthetization was shorter that five minutes. The test substance was then applied to the anaesthetized bees; and the treated bees were then returned to the test cages and kept under test conditions for 48 hours. Five dosages of the test substances were tested in order to provide a rational base for a proper assessment of the control LD₅₀ of microencapsulated chlorpyrifos to honey bees. The anaesthetized bees are laid, ventral surface up, on filter paper in petri dishes. One μl drop per bee of microencapsulated chlorpyrifos in solvent was placed in the ventral thorax using a GC-syringe.

The result was an LD₅₀ contact of 22.1 μ/bee compared to a toxicity of 0.059 μ/bee for technical chlorpyrifos,

C. Oral Toxicity Test

Five dosages of microencapsulated chlorpyrifos in acetone were tested in order to provide a rational base for a proper assessment of the oral LD₅₀ to honey bees. Ten cages containing 10 bees each were prepared without food, letting the bees starve for 1 to 2 hours. Following this, 250 μl of the prepared solutions in type of Eppendorf-pipettes were hung in each cage through one of the top openings. The bees were observed as long as uptake of the solution takes place. Each bee that vomited the solution was excluded from the test. The bees were provided with normal food after the uptake of the tested solution, but at the latest after 3 hours.

The result was an LD₅₀ oral of 118.5 μ/bee compared to a toxicity of 0.25 μg/bee for technical chlorpyrifos.

EXAMPLE 10 Representative Preparation of the Microencapsulation of Endosulfan

Following the general method of Example 1 four solutions, A-D were prepared.

    ______________________________________                                         Solution A: 380 ml water                                                                   3.8 g polyvinyl alcohol (MOWIOL-G4)                                Solution B: 180 g melted endosulfan                                                        42 g Voranate M-580                                                            1 g "TINUVIN-770"                                                              1 g Irganox 1076                                                   Solution C: 9 g water                                                                      9.3 g tetraethylinepentamine                                                   5.6 g Diethylene triamine                                          Solution D: 3.5 g propylene glycol                                                         14.6 g Nonylphenol 6 moles ethoxylated                                         (NP-6)                                                                         2.5 g xanthan gum                                                  ______________________________________                                    

Solution A is heated to 80° C. and Solution B is added and an emulsion is made using a high sheer mixer for 1-2 minutes. Solution C is then added and the reaction mixture is stirred for an additional 4 hours keeping the temperature of the mixture at 50° C. The pH of the solution is then reduced to 7.6 by adding H₃ PO₄, Solution D is added, and the reaction mixture stirred for 15 minutes. Representative microencapsulated composition of endosulfan are listed in Table 9 and 10.

                                      TABLE 9                                      __________________________________________________________________________                                                    Nonyl-                                                                         phenol                                                                         6 mole                                                         Propyl-                                                                             Tetra-                                                                               Propyl-                                                                             ethoxy-                                                                            Xan-                        Isocyantes     Ethylene                                                                            Diethylene                                                                           U.V. ene- ethylene                                                                             ene  lated                                                                              than                                                                              Other                    Sample    Quantity                                                                            diamine                                                                             triamine                                                                             absorb-                                                                             diamine                                                                             pent- gly- (NP-6)                                                                             gum                                                                               add- Conc.               Number                                                                              Type (g)  (g)  (g)   er: (g)                                                                             (g)  amine: (g)                                                                           col: g                                                                              %   (g)                                                                               tives                                                                               a.i.                __________________________________________________________________________                                                                %                   31   Voranate                                                                            11.7 2.0  1.9   Tinuvin                                                                             --   --    1.2  14.6                                                                               2.7                                                                               --   25.8                     M-580                770                                                  32   Voranate                                                                            11.7 --   1.9   Active C                                                                            2.6  --    1.5  14.6                                                                               2.7                                                                               --   --                       M-580                                                                     33   Voranate                                                                            11.7 2.06 1.9   Active C                                                                            --   --    1.5  14.6                                                                               2.7                                                                               --   --                       M-580                                                                     34   Voranate                                                                            11.7 --   1.9   Active C                                                                            2.6  --    1.5  14.6                                                                               2.7                                                                               --   --                       M-580                                                                     35   Isonate                                                                             11.7 2.0  1.9   Tinuvin                                                                             --   --    1.5  14.5                                                                               2.7                                                                               --   --                       M-301                770                                                  36   Isonate                                                                             11.7 --   1.9   Tinuvin                                                                             2.6  --    1.5  14.6                                                                               2.7                                                                               --   --                       M-301                770                                                  37   Voranate                                                                            11.7 1.86 1.71  Tinuvin                                                                             --   --    1.2  14.6                                                                               2.7                                                                               --   24                       M-580                770                                                  38   Voranate                                                                            11.7 1.86 1.71  Tinuvin                                                                             --   --    1.2  14.6                                                                               2.5                                                                               --   25                       M-580                770                                                  39   Voranate                                                                            11.7 1.86 1.72  Tinuvin                                                                             --   --    1.2  14.6                                                                               2.5                                                                               --   25                       M-580                770                                                  40   Voranate                                                                            35   5.6  5.3   Tinuvin                                                                             --   --    3.5  14.6                                                                               2.5                                                                               Ca(No.sub.3).sub.2                                                                  17                       M-580                770                                                  41   Voranate                                                                            35   5.6  5.2   Tinuvin                                                                             --   --    3.5  14.6                                                                               2.5                                                                               --   --                       M-580                770                                                  42   Voranate                                                                            35   5.6  5.3   Tinuvin                                                                             --   --    3.5  14.6                                                                               2.5                                                                               --   --                       M-580                770                                                  43   Voranate                                                                            35   5.6  5.3   Tinuvin                                                                             --   --    --   2.5 -- --   --                       M-580                770                                                  44   Voranate                                                                            35   --   5.3   Tinuvin                                                                             --   8.69  --   2.5 -- --   --                       M-580                770                                                  45   Voranate                                                                            35   --   5.3   Tinuvin                                                                             6.9  --    --   --  2.5                                                                               --   --                       M-580                770                                                  46   Isonate                                                                             35   5.6  5.3   Tinuvin                                                                             --   --    3.5  --  2.5                                                                               --   --                       M-301                770                                                  47   Voranate                                                                            35   --   --    Tinuvin                                                                             6.9  8.64  7.0  14.6                                                                               2.5                                                                               --   --                       M-580                770                                                  48   Isonate                                                                             35   --   5.3   Tinuvin                                                                             6.9  --    3.5  --  2.5                                                                               --   --                       M-301                770                                                  49   Voranate                                                                            18   --   5.3   Tinuvin                                                                             --   8.64  3.5  14.6                                                                               2.5                                                                               --   --                       M-580 +                                                                             17              770                                                       TDI                                                                       50   HMDI 26.1 5.6  5.3   Tinuvin                                                                             --   --    --   14.6                                                                               -- --   --                                            770                                                  51   TDI  26.1 5.6  5.2   Tinuvin                                                                             --   --    --   --  -- --   --                                            770                                                  52   TDI  26.1 --   5.7   Tinuvin                                                                             7.7  --    --   --  2.5                                                                               --   --                                            770                                                  53   HMDI 26.1 --   5.7   Tinuvin                                                                             7.7  --    --   14.6                                                                               -- --   --                  __________________________________________________________________________

                                      TABLE 10                                     __________________________________________________________________________                                  Nonyl-                                                                         phenol                                                                         6 mole                                                                         ethoxy-                                           Sample                                                                              Isocyanates                                                                              Amines   Irganox                                                                             lated                                                                               Xanthan                                                                             %                                       Number                                                                              Type Quantity                                                                            Type                                                                               Quantity                                                                            1076 gr.                                                                            (NP-6)                                                                              gum  a.i.                                    __________________________________________________________________________     54   Isonate                                                                             38.5 DETA                                                                               5.0  1    Solid                                                                               --   19.4                                         M-342     PDA 6.8       additive                                          55   Voranate                                                                            45.5 DETA                                                                               5.93 1    Solid                                                                               --   21.3                                         M-580     PDA 8.06      additive                                          56   Voranate                                                                            38.5 DETA                                                                               5.01 1    Solid                                                                               --   23.8                                         M-580     PDA 6.8                                                         57   Voranate                                                                            42   DETA                                                                               5.7  1    Solid                                                                               14.8 26.0%                                        M-580     PDA 7.4       Liquid                                                                              2.5                                          58   Voranate                                                                            42   DETA                                                                               5.57 1    Solid                                                                               14.8 30.7%                                        M-580     PDA 9.54      Liquid                                                                              2.5                                          59   Isonate                                                                             42   DETA                                                                               5.57 1    Solid                                                                               14.8 25.1%                                        M-342     PDA 7.4       Liquid                                                                              2.5                                          60   Isonate                                                                             42   DETA                                                                               5.57 1    Solid                                                                               14.8 25.2%                                        M-310     TEPA                                                                               9.3       Liquid                                                                              2.5                                          61   Isonate                                                                             42   TEPA                                                                               9.3  1    Solid                                                                               2.5  25.6%                                        M-342     DETA                                                                               5.57      Liquid                                            __________________________________________________________________________

EXAMPLE 11

Following the method of Example 3, the two best microencapsulated formulations of the present invention containing endosulfan were listed for their toxicity to non-target species, represented by mice. The results are shown in Table 11. This shows the lower toxicity of formulation 61 as against formulation 59.

EXAMPLE 12

Following the method of Example 6, the two best microencapsulated formulations of the present invention containing endosulfan were tested for their toxicity to non-target species, fish, compared with the non-microencapsulated EC-35 formulation. The results are shown in Table 12. This shows the lower toxicity of formulation 61 as against both formulation 59 and against the non-microencapsulated EC-35 formulations of endosulfan.

                  TABLE 11                                                         ______________________________________                                         THE TOXICITY TO MICE OF THE                                                    TWO BEST MICROENCAPSULATED                                                     FORMULATIONS OF ENDOSULFAN.sup.a                                               Exposure                                                                              Formulation No. 59                                                                               Formulation No. 61                                    Time in                                                                               Solution concentration - mg/kg                                          Hours  33.3   50     75   112.5  33.3 50   75   112.5                          ______________________________________                                          1      0      50     50   50     0    0    0    0                              3     50      50    100  100     0    20  100  100                             24    50     100    --   --      0    50  --   --                              48    50     --     --   --     50   100  --   --                              72    50     --     --   --     50   --   --   --                             168    50     --     --   --     50   --   --   --                             ______________________________________                                          .sup.a Percent mortality.                                                

                                      TABLE 12                                     __________________________________________________________________________     THE TOXICITY TO FISH OF THE TWO BEST                                           MICROENCAPSULATED FORMULATIONS OF ENDOSULFAN.sup.a                                     EC-35  Formulation No. 59                                                                          Formulation No. 61                                 Exposure Time                                                                          Solution concentration - mg/l                                          in hours                                                                               1 5 10 2.5                                                                              5 8 16                                                                               50                                                                               100                                                                               2.5                                                                              5 8 16                                                                               50                                                                               100                                      __________________________________________________________________________      3      0  0                                                                                30                                                                               0  0                                                                                0                                                                                0                                                                                0                                                                                0 0 0  0                                                                                0                                                                                0                                                                                0                                        6      0  0                                                                                30                                                                               0  0                                                                                0                                                                               10                                                                               10                                                                                0 0 0  0                                                                                0                                                                                0                                                                                0                                       24      0 57                                                                                70                                                                               0 20                                                                               20                                                                               40                                                                               43                                                                               100                                                                               0 0  0                                                                                0                                                                               20                                                                                50                                      48      0 57                                                                               100                                                                               0 20                                                                               30                                                                               40                                                                               71                                                                               -- 0 0 30                                                                               30                                                                               30                                                                               100                                      72      0 57                                                                               -- 0 20                                                                               30                                                                               40                                                                               71                                                                               -- 0 0 30                                                                               30                                                                               40                                                                               --                                       96      0 57                                                                               -- 0 20                                                                               30                                                                               40                                                                               71                                                                               -- 0 0 30                                                                               30                                                                               40                                                                               --                                       __________________________________________________________________________      .sup.a Percent mortality.                                                 

I claim:
 1. A microencapsulated composition comprising particles having a shell consisting essentially of a polyurea and a pesticide encapsulated within said shell, said pesticide being selected from the group consisting of chlorpyrifos and endosulfan, and wherein said particles also comprise one or more photostable ultraviolet and visible light absorbent compounds having a log molar extinction coefficient of from about 2 to 5 with respect to radiation having wave lengths in the range of about 300 to 500 nanometers, said photostable ultraviolet and visible light absorbent compounds being selected from those which do not react with the monomer used in building the polyurea shell.
 2. A composition in accordance with claim 1 wherein the photostable ultraviolet and and visible light absorbent compounds are selected from the group consisting of sterically hindered amines and dyes.
 3. A composition in accordance with claim 2 wherein the sterically hindered amines are selected from the group consisting of "TINUVIN 770" and "TINUVIN 780".
 4. A composition in accordance with claim 3 wherein the sterically hindered amine is "TINUVIN-770".
 5. A composition in accordance with claim 2 wherein the dyes are selected are selected from group consisting of Thermoplast green, Blue paste Fluorescein, Sudan Blue, Macrolex blue and Sudan III.
 6. A composition in accordance with claim 1 wherein the percentage of the envelope--excluding the water and polyvinyl alcohol--varies from 3% to 50%.
 7. A composition in accordance with claim 6 wherein the percentage of the envelope--varies from 10% to 30%.
 8. A composition in accordance with claim 1 wherein the fill contains from 0.57% to 5% of the photostable ultraviolet and visible light absorbent compound.
 9. A composition in accordance with claim 8 wherein the fill contains from 1% to 3% of the photostable ultraviolet and visible light absorbent compound.
 10. A composition in accordance with claim 1 having a high toxicity to target species while having a very low toxicity to non-target species, wherein said microcapsule particles are formed by interfacial polymerization.
 11. A microencapsulated composition comprising a polyurea shell, chlorpyrifos and a photostable ultraviolet and visible light absorbent sterically hindered amine selected from the group having the trade names "TINUVIN 770" and "TINUVIN 780".
 12. A composition in accordance with claim 11 wherein the sterically hindered amine is "TINUVIN-770".
 13. A composition in accordance with claim 11 wherein the composition also contains dyes selected from the group consisting: of Thermoplast green, Blue paste Fluorescein, Sudan Blue, Macrolex blue and Sudan III.
 14. A composition in accordance with claim 11 having a high toxicity to target species while having a very low toxicity to non-target species.
 15. A microencapsulated composition comprising a polyurea shell, endosulfan, and a photostable ultraviolet and visible light absorbent sterically hindered amine selected from the group having the trade names "TINUVIN-770" and TINUVIN-780".
 16. A composition in accordance with claim 15 wherein the sterically hindered amine is "TINUVIN-770".
 17. A composition in accordance with claim 15 wherein the composition also contains dyes selected from the group consisting of Thermoplast green, Blue paste Fluorescein, Sudan Blue, Macrolex blue and Sudan III.
 18. A composition in accordance with claim 15 having a high toxicity to target species while having, a very low toxicity to non-target species.
 19. A composition in accordance with claim 2 wherein the percentage of the envelope--excluding the water and polyvinyl alcohol--varies from 3% to 50%.
 20. A composition in accordance with claim 19 wherein the fill contains from 0.5% to 5% of the photostable ultraviolet and visible light absorbent compound. 